Fire-alarm system



1,620,10? March J. M. JOHNSON FIRE ALARM SYSTEM Filed March 22, 1922 7 Sheets-Sheet 1 W-ZZHGGO': -lNVE[\|TO R.'

. y 71 Johnson, I J0 72 M.

ATTORNEY.

March 8, 1927.

1,620,107 J'. M. JOHNSON FIRE ALARM SYSTEM 5 March 22. 1922 '7 Sheets-Sheet 5 ATTORNEY.

March 8, 1927.

J. M. JOHNSON FIRE ALARM SYSTEM Filed March 22, 1922 '7 Sheets-Sheet 4 img INVENTOR. Ja/znMJaimsan,

ATTORNEY.

IKZZIIG J 5 March 8, 1927.

J. M. JOHNSON FIRE ALARM SYSTEM Filed March 22. 1922 7 Sheets-Sheet 5 Wlfhass: wad/awagw Patei'ited Ni 8, i921 STATES JGHN IiI. JOHNSON, OF KANSAS CITY, IEISS OUELE, ASSZGNGE TO THE UNITED STATES AUTOMATIC FIRE ALARM COMPANY, A COREQBATIOH OF MISSOURI.

FIRE-ALARM SYSTEM.

Application filed March 22,

lhis invention relates to automatic fire alarm systems, and one objectis to produce a new and useful system of this character whereby fire occurring in a building Within a certain block will, in its incipiency, transmit signals to a central station, giving the location of the street, the number of the building, and the floor on which the fire oc curs, so that it can be readily located and extinguished before the building is damaged to any great extent.

A rurther object is to provide an automatic system which is operative under such 'ble accidents as short circuits and in the main and house circuits, or in the thermostatic circuit closers employed; instantly transmitting to the central station a signal distinct from the fire alarm signal, of such accidents so that re pairs can be promptly made.

Another object is to provide system of this character whereby in the event that a tire should follow any of the accidents above-mentioned before repairs are made, said system will transmit to the central station a signal indicating such tire after transmitting; the signal indicating the accident.

ln order that the i vention may be fully understood, reference will now be made to the accompanying drawings, in which:

Fig. 1 is a di gram oi? the central station eouie-ment in normal condition.

big. 2 18 a diagram or two house equipand the equipr" t at the outer termithe main 5 nus 01" house equipment ":JOVVS ill 1 louse equipment in the 1 emergency lire alarm i of the trouble alarm house loop. .i' use loops cut out from {3 shows the house equipment in the r: transmitting an emergency fire alarm with both. of the house loops broken.

1922. Serial no. 545,783.

Fig. is a diagram showing one of the main signal circuit wires broken.

Fig. 8 is a plan View of one of the thermostatic circuit closers.

Fig. 9 is a vertical section on line IX1X of Fig. 8.

Fig. 10 is a side elevation of one of the signal trz'insmitters.

Fig. 11 is a Vertical sectional View of said signal transmitter, taken on line XI-XI of Fig. 13.

Fig. 12 is an end View of the signal transmitter with some or" the parts removed.

Fig. 13 is aplan View of the signal transmitter.

The central station 1 generally by the reference ha 1), indicated acter A, emequipment a test, or milli-ampere meter; meter; 8 a voltmeter, and 9 another relay. All of the foregoing may be of preferred or any ordinary type, excepting that the test meter 6 has an extra contact 11 for controlling the circuit to the bell The recorder 3 is in a normally open circuit comprising a conductor 20 connected to one pole of said recorder 3 and a contact point 15 associated with the pivoted armature 13 of the relay 1, a conductor 21 connected to the opposite pole of the recorder 3 and one side 23 of the main al circuit, a conductor 24 connected to the opposite side 25 of said main signal circuit and the relay armature 13.

The bell l is in a normally open circuit including a conductor 27 connected at its ends to one pole of said bell 1 and a contact 16 associated with the drop armature 14: of the relay 2, a conductor 28 connected at its ends to the opposite pole of the hell 4 and the side 25 ot the main signal circuit, and a conductor 29 connected at its ends to the drop armature 14 and the side 23 of the main signal circuit.

The hell 5 is in a normally open circuit comprising a conductor 31 connected at its ends to the main signal circuit wire 23 and one pole of said bell 5, a conductor 32 connected to the opposite pole of the bell and a contact 33, and a conductor 3% connectedto the main signal circuit wire and the drop armature 35 of the relay 9.

The fixed contact point 11 of the meter 6 is connected by wire36 to the relay 9 and the conductor 27, and is spaced from one side of the pointer 37 ot the meter 6 to allow said pointer to oscillate and thus indicate certain fluctuations in the main signal circuit 23, 25, without actuating the bell 5. However, on an increase oi current in the main. circuit the pointer 37 will swing into engagement with the contact 11 and close the circuit through the hell 5. One pole or" the test meter 6 is connected by a wire 38 to the main signal circuit wire 23, and the opposite pole is connected to the main signal circuit wire 25 through a conductor 39 and the coils of the relays 1 and 2.

The ammeter 7 is in series with the main signal circuit wire 23, while the voltmeter 8 is connected across the main signal (311131115 22 to be thrown into contact with either side of said main signal circuit in case of a broken wire. A resistance coil 22 is llltGI'POEQCl be tween the switch 22 and its grounded side to prevent accidental short-circuiting of the main signal circuit through the ground and.

said switch 22, due to proximity of high volt age power systems prevalent in large cities.

The outer terminus 2), of the main signal circuit is connected to a resistance coil 40 and the wires 23 and 25 are also connectet to electromagnets l1 and 42, which normally attract their armatures 4-3 and 44- against the action of springs 45 and 46, which tend to draw said armatures into engagement with contacts 47 and as connected to grounding coils a9 and 50, respectively. The arn'iatures 43 and e l are connected to the main signal circuit wires 23 and 25 by leads 51 and 52,

respectively. Under normal conditions the resistance coil a l) conserves current and in case of fire or other trouble the current will pursue a. less resistant path than-that to the terminus of the main signal circuit, as will hereinafter appear.

A charging circuit is, preferably, located at the central Station A to eliminate the expense of taking care of different groups of batteries in each building or block of building's. As shown by Fig. 1, two sets of batteries 50 51, are employed, so that one set can be recharged while the other set is serv ing the system. The batteries 50 and 51 are in circuits 52, 53, respectively. The battery circuit 52 is equipped at its term.-

nals with knife. switches 54 and 5.5, the

former to connect the circuit 52 and the main signal circuit 23, 25, while the switch 55 is adapted to connect the battery circuit 52 and a supply circuit 56, energized from a suitable source such as a dynamo 57. The circuit 53 is provided at its ends with knife switches 58 and 59, the former to establish connectionwith the main signal circuit 23, 25, and the latter with the supply circuit 56.

Each house equipment (Figs. 2 to 7, inclusive), designated in general by the reference eharacter..B, embodies a plurality of thermostatic circuit closers and a signal transmitter 7 Equipment for two floors of a building to be protected are shown by Fig. 2. Each floor has a. set of thermostatic circuit closers 75' in circuit with a signal transmitter '76. Each set may contain any desired number of circuit closers 75, which are located to the best advantage. For convenience o1 inspection all the signal transmitters 76 may be located on one floor, but each or course will be connected to its respective set of thermostatic circuit closers 75.

Each thermostatic circuittcloser 75 (Figs. 8 and 9), consists,preferably, of a glass tube 7 3 having ab-ulb of mercury 74., lengths of wires 77 fused into the glass tube 73 and in circuit with the mercury, and a wire 78 fused into the tube 73 and entering the bore there of above the mercury at such point that when the temperature rises to a predetermined degree, for example 160 degrees F., the mercury expands into contact with. said wire 78 and results in the transmission of a fire alarm signal to central station A. The wires 77 ofv the different thermostats are connected. outside ot the tubes 73 to constitute a normally closedhouse loop which is in series with the main signal circuit wire 23. The wire 78 constitutes another normally closed hous. loop and is connected across the main signal circuit 23, 25 through the instrumentality of a switch 79 and certain of its contacts hereinafter described.

Each signal transmitter 7.6 is designed for the transmission of a fire alarm; a trouble alarm in case either of the main signal circuit loops 23, 25, or the house wires 77, 78, become short-circuited or broken; an en'iergcncy fire alarm signal which may be transmitted after a trouble alarm any time before the transmitter is manually reset for operation; and means for restoring the systQHLlJO operative condition after the transmission of any of the aforementioned alarms.

Each signal transmitter 75 (Figs. 10 to 13, inclusive), embodies the aforementioned switch 7 9 which is provided with multiple blades 82 to 89, inclusive; a: set of contacts 90 to 9'7, arranged to be engaged by the respective blades 82 to 89, inclusive; a and set or contacts 100 to 105, adapted to be engaged by the respective blades 82 to lllfi 87, inclusive when the switch 79 changes its position; a latch 110 to engage the switch 79 and normally hold the blades 82 to 89 in engagement with the respective contacts 90 to 97, inclusive; an armature 112 fixed to a lever 112 fixedly mounted upon the latch shaft 111; a trip magnet 11 1 adapted to attract said armature 112 and cause itto disengage the latch from the switch 79, so that a. spring 115 may rock said switch 79 and cause the same to carry the blades 82 to 87, into engagement with the respective contacts 100 to 105, inclusive; a magnet 17; a make-and-break switch 119; two pairs of contacts 120, 122, associated with said switch 119, and connected to the main signal circuit wires 23, 25, respectively; a codewheel 128 for intermittently closing the switch 119; a spring 130 to open the switch 119; a Geneva wheel 132 driven step by step by a wrist pin 134 fixed to said codewheel 128; a normally closed switch 136 adapted to be opened by a lug 133 on said Geneva wheel 132 and check the rotation thereof to the right; a detent 138, which normally depends into the path of a lug 133 on the Geneva wheel 132, so that when a trouble signal is sent in, said detent 138 will check said Geneva wheel 132 before the same can open said switch 136; an elec tromagnet 140, to raise the detent 138 out of the path of the Geneva wheel 132 so that a fire alarm signal may be transn'litted and the Geneva wheel 132 may rotate until its lug 133 opens the switch 136; a normally open switch 142 connected across the main si 'nal circuit 23, 25 and adapted to be closed by a cam 1 14: arranged to rotate with the Geneva wheel 132; a release magnet 1 16; an arn'iature 1 18 arranged to be actuated by said release magnet 146; a lever 148 mounted upon a rock shaft 148 and carrying the armature 1 18; and a governor 150, which, when released by the armature lever 148, permits a spring-actuated train 152 to drive the code-wheel 128. The code wheel 128 of each transmitter 76 has its particular arrangement of peripheral teeth 129 and indentations to coact with the associate malze-and-break switch 119 in transmitting its respective code to the central station A.

The armature lever 1 2f is normally held against a stop 200 by a spring 202 and thus, through the intermediacy of the shaft 111 and the latch 110, holds the switch 79 in the position disclosed by Fig. 10. The armature lever 148 is normally held in the path of the governor 150 by a transverse arm 1%8 fixed thereto and yieldably engaged by a spring 20% fixed to the armature lever 112, 11 to 13, inclusive. l lhen the electromagnet is energized, as will hereinafter appear, it attracts its armature 1&8, which in. turn raises the lever 1&8 out of the path of the governor and thereby releases the code wheel driving train 152, the speed of which is regulated by the governor escapemcnt 206 which oscillates with the governor. The armature 143, is prevented from moving down into the path of the oscillating governor 150 b stop 208, which is swung by a sprir beneath said lever 148 The stop shatt has a short arm 21% with an outturned end 216 passing through a hole 218 in the transmitter frame to limit the rocking movement of the stop 208. A manually controlled lever 220 normally held in raised position by a spring 222, is provided for holding the make-and break switch 119 in engagement with the contacts 120, 122, 123 and 12 1- and thus preventing the transmission of signals during winding of the spring 224: which drives the code wheel train 152. Said lever 220 has a lateral projection 226, so that when depressed to hold the switch 119 in closed position, as stated, said projection 226 will engage the short arm 211 and rock the stop 208 from beneath the armature lever 1 1-8 so that the same may move down into the path of the governor 150 and cause it to lock the train 152 from accidental rotation after the spring 221 has been wound.

lVhen the electromagnet ll-G is energizer by abnormal conditions in the house loops and releases the code wheel train 152 as stated, the latch 110 holds the switch 9 in the normal position disclosed by Fig. 10, until the lug 133 on the rotating Geneva wheel 132 engages the outturned end of a push rod 133 fixed to the armature lever 112 which is thereby caused to rock the shaft 111 and disengage said latch 110 from the switch 79, so that the same may be moved into engagementwith the contacts 100 to 105, inclusive, by the spring 115.

Before and after the code wheel 128 has been actuated to transmit an alarm it holds the switch 119 closed through the intermediacy of a pin 230 projecting laterally from said switch 119.

The construction and operation of that portion of the signal transmitter 76, disclosed by Figs. 12 and 13., is substr tiallv the same that portion of the transir disclosed by Figs and 5 in United Sta Letters Patent No. 1,484.713, of Fe 26, 192%. I I

The coil of the electrcmagnct 117 is of relatively high resistance to materially reduce the current flowing through the house loop 78 and allow only suflicient current. to pass therethrough to normally retain a circuitbreaker 15% in engagement with i s centact 105 and thus coact with the sw 1 T9 in normally holding th hour: closed.

As an aid to tra cuits established b 76 and by reason of fires, brokenwires, etc.,sai'd circuits have been shown in heavy hnes on the drawings,

in which Fig. 1 and the upper portion of Fig. 2, show the circuits in normal condition.

The normal path otthe current may be traced from the battery 50 through the right side of switch 54, signal circuit wire 23, ammeter 7, signal circuit wire 23, wire 38, test amnieter 6, the coil of relay 1, wire 39, the coil of relay 2, signal circuit wire 23, make-and-break contact 120 of the upper section of the house equipment 1B, makeand-break switch 119, contact 122, signal circuit wire 23, contacts 93 and 85, switch 79, contacts 84 and 92, wire 77,.circuit breaker 154, contact 155, house loop 77 and the thermostatic circuit closers 75, thence through signal circuit wire 23 to the lower section of the house equipment 13, through which it pursues the same course as in said upper house section, thence through the signal circuit wire 23, coil 41, resistance 40, signal circuit wire 25, coil 42, signal circuit wire 25, contact 126, niake-and-break switch 119, contact 124, signal circuit wire 25, contact 126, make-and-break switch 119 of the upper house section, contact 124, gnal circuit wire 25, and back to the battery 50" through the left side of switch 54.

In addition to the above circuits there s a norn'ially energized branch circuit in the central station equipment through wire 41 leading from the signal circuit wire 23 to voltmeter 8, thence through line 42 and back to the battery 50 through the signal circuitwire There are also slightly energized shunts in each house section B consisting of a wire 172, the signal circuit wire 23, contact 94, switch 7 9, contact 95, and to signal circuit wire 25 through line 166. The

trip magnet, or trouble coil 114, in line 166 coacts with the resistance 40 and the coil 117 in normally reducing the current flowing therethrough to aminimum, so that it cannot energize said coil 114 sufficiently to cause it to release the signal transmitter 75, until strengthened as hereinafter pointed out. Each house section also has a house loop 78 connected at one end to the signal circuit wire 23 from which latter current flows through said line 78, the high resist ance testcoil 117, wire 78, contact 90, blades 82 and 83 of switch 79, contact 91, wire 78, contact 97, switch blades 89'and 88, contact 96, and through wire 78 to the signal circuit wire 25'. A fire alarm coil 146 connected to the wire 78 coacts with the test coil 117 and the resistance 40 in reducing the current flowing through the house loop 78 to a. minimum, so that it is normally too weak to cause said coil 146 to releasethe transmitter 76, until strengthened by current from the loop 77, as hereinafter described. i

In Fig. 2, the lower section thereof shows the condition of the house equipment when a fire occurs and closes one of the circuit closers 75, as indicated at F. This opens a path of less resistance to the current than switch blades 89 and 88, contact- 96, and wire 78 to the main signal circuit wire 25. The increased current passing through that portion of the wire 78 leading to the main line 25 causes the magnet 146, to draw its armature 148, Figs. 10 and 11, out of the path of the governor 150, causing it to release the train 152 which then drives the code wheel 128. As the code wheel 128 describes its first revolution, it, through the intermediacy of the Geneva wheel 132 and the cam 144, closes the switch 142, which positively short-circuits that portion of the main signal circuit extending from the house equipment transmitting the signal to the resistance coil 40 until the code wheel 128 makes its last revolution when the cam 144 passes from beneath the switch 142 and allows the same to open. By thus positively short-circuiting that portion of the main signal circuit 23, 25, at the rear of the transmitter transmitting the fire alarm signal the full force of the current is not only caused to fiow through said transmitter and thus insure positive transmission of the signal, but the house equipments at the rear are prevented from transmitting interfering signals.

As the code wheel 128 revolves, it and the spring 130 alternately actuate the makeandbreak switch 119, causing the same to transniit the code to the relay 1, the armature 13 of which operates in synchronism with the switch 119 and transmits said code to the recorder 3 through the circuit including the wire 21 leading from the main signal circuit wire 23, the recorder 3, wire 20, contact 15, the armature l3, and the wire 24 leading to the main signal circuit wire 25.

At the first interruption of the main signal circuit caused by the initial opening of the makeand-break switch 119 when trans mitt-ing the code, the relay coil 2 at central station :1 becomes momentarily deenergized and permits the armature 14 to drop into engagement with the contact 16, thus closing the circuit including the alarm bell 4, wire 29 leading from the main circuit wire 23, armature 14, contact 16, wire 27, and the wire 28 leading to the main signal circuit mostat at F, the house loop 78, contact 97,

Gil

Wire 25. The armature 14 by remaining in engagement with the contact 16 until manually restored to normal position, indicates which main signal line, where there are a plurality, transmitted the signal. The hell 4 continues to ring until its circuit is inter" i'upted by manually restoring the armature 14 to normal position as stated. As the impulses are transmitted by the make-andbreak switch 119 to the central station A, they cause the pointer 37 of the meter 6 to vibrate and close the circuit leading from the main signal circuit wire 23, through an1- meter 7, wire 38, milliamperemeter 6, contact 11, wire 36, solenoid 9, bell 4, and the wire 28 leading to the main signal circuit wire 25. This energizes the electromagnet 9 which trips the latch 10 and permits the armature 35 to drop into engagement with the contact 33 closing the circuit including the bell 5, wire 31 leading from the main signal circuit wire 23, wire 32, contact 33, a mature 35, and wire 34 leading to the main signal circuit wire 25. The hell 5 rings until its circuit is interrupted by manually restoring the armature into engagement with the latch 10, which operation, however, is deferred until the code wheel 128 comes to rest. As the code wheel 128 moves the Geneva wheel 132 through its final step the lug 133 on said Geneva wheel 132 engages the outer end of the push rod 133, Figs. 10 and 11, which rocks the armature 112 and its shaft 111, causing the latter to raise the latch 110 and thus permit the spring 115 to swing the switch 79 into en gagement with the contacts 100 to 105, inclusive, Fig. 5. As the code wheel 128 describes its last revolution, cam 144 allows the short-cirouiting switch 142 to open and the lug 133 on the Geneva wheel 132 opens the switch 136 by pushing upwardly on the lowermember thereof. After the switch has been opened it checks further movement of said Geneva wheel 132 and the code wheel 128. Opening of the switches 136 and 142 clears the main signal circuit 23, 25, which is closed through a shunt (Fig. 5), consisting of a wire 17'!" leading from the main signal circuit wire 23, contact 100, switch blades 82, 83, contact 101, and a wire 178 leading to the other side of said main signal circuit wire 23. Thus while the transmitter 76 which just sent in the fire signal as stated, is unable to transmit other signals until manually restored to normal position (upper portion of Fig. 2), the main signal equipment 23, 25, is left in condition for the transmission of signals by any other house circuit connected to the main circuit.

Fig. 3, shows how a trouble signal is sentto the central station A, in case the house loop 77 becomes broken as indicated at H. As shown the current is shunted by the transmitter 76 throughthe line 172 leading from the main signal circuit wire 23, contact 94, switch blades 86 and 87, contact 95, and wire 168 leading to the other side of the main signal circuit wire 23. This energizes the electro-magnet 114, Figs. 10 and 11, causing it to attract its armature 112, which, through the intermediacy of transverse arm 148, raises the armature 148 out of engagement with the governor 150, thus freeing the train which drives the code wheel 128. The armature 112 also disengages the latch 110, permitting the spring 115 to throw the switch 79 into engagemet with its contacts 100 to 10.3, inclusive, 4. When the switch 79 is thrown to the last-mentioned position it carries the arm 108 from beneath the detent 138, which is immediately forced by a spring 139 into the path of the lug 133 on the Geneva wheel 132 and checks the same, together with the code wheel 128 as the same completes one revolution. As the code wheel 128 makes revolution it actuates the make-and-break switch 119, which transmits the code to the central station A over the main signal circuit wire 25, the wire 21, recorder 3, wire 20, contact 15, armature 13, and the wire 24. The recorder 3 prints the code but once instead of repeating as in the case of a tire and thus makes a distinction between the trouble and fire signals. The circuit including the hell 4 is also closed as in the fire alarm, causing said hell 4 to ring until the armature 14 is manually restored to normal position. As the switch 142 is not closed to cut out the resistance 40, the meter 6 is not aifected suiiicientiy to close the circuit to the bell 5, thus maxing another distinction between the tire and trouble signals. After the trouble signal is transmit ted the main signal circuit 23, 25, is left closed through wire 177 leading from the main signal wire 23, contact 100, blades 82 and 83, contact 102, and wire 17 8 leading to the other side of said main signal wire 23, for the transmission of an emergency fire alarm by the transmitter 76 which just turned in the trouble alarm as stated, and also for the tran mission of signals by any other house equipment. The foregoing op erations also take place in case a circuit breaker 75, should become broken and let the mercury run out. Should the house loop 78 become broken instead of the house line 77, the coil 117 becomes deenergized and permits the circuit breaker 154 to interrupt the current passing through the house loop Ti' and a trouble signal is transmitted in the same manner as above-described.

4 shows in heavy lines the house equipment transmitting a fire alarm following either of the trouble signals above-dcscribed. The closing of one of the thermostats at G by the rising temperature closes a circuit leading from the main signal circuitwire 23, through wire 177, contact 104, blades 86 and 87 ,contact 105, wire 17 5, house loop 77 the closed thermostat at G, house loop 78, wire 170, switch 136, wire 170, contact 102, blades 84 and 85, contact 103, wire 176, and through wire 78 to the main signal circuit wire 25. The circuit through the wire 170 energizes the electromagnet 140, which raises the detent 138 out of the path of the lug 133 permitting the Geneva wheel 132 and the code wheel 128 to act and complete the fire alarm circuits at central station, asset forth in the description of the initial fire alarm circuit. After transmis sion of said emergency fire alarm the main signal circuit 23, 25, is left closed in the same manner as after the transmission of a regular fire alarm previously described.

Fig. 5 discloses in heavy lines how the main signal circuit 23, 25, is closed for the transmission of signals from any other house equipment after one of the house circuits has transmitted a regular fire alarm, or an emergency fire alarm as above described and has been cut off from said main signal circuit. As shown the current passes from the main signal circuit Wire 23, to the wire 1777, contact .100, blades82 and 83, contact 101, and from wire 178 to the other side of the main signal circuit Wire 23.

Fig. 6 discloses by heavy lines how in case a fire follows two broken house loops 77 ans 78, an emergency fire alarm can be transmitted over the main signal circuit 23, 25. hen the house loops 77 and 7 8 break as indicated at I and J, a trouble alarm is sent to the central station A, in the same manner as described when referring to Fig; 3. When the rising temperature caused by a fire closes one of the thermostats 7 5 as indicated at K, Fig. 6, current from the main circuit line 23 passes through the wire 177, contact 100, blades 82 and 83, contact 101, wire 17 8, house loop 77, the closed thermostat at- K, house loop 78, wire. 170, switch 136, wire 170, contact 102, blades 84 and 85, contact 103, loop 176, and through loop 78 to themain signal.

circuit wire 25. The action at the central station A is the same as when a trouble signal is sent in followed by an emergency fire alarm signal as hereinbefore described; After the fire alarm has been transmitted the main signalcircuit 23, 25 is left intact as shown by Fig. 5.

Fig. 7 is a diagram showing a break in the main signal circuit wire 23. This results in deenergizing the house and the main circuit. The relay armature 13, Fig. 1, drops against the contact 15 and closes the circuit to the recorder 3, which runs out tape but does not print as none of the transmitters 76 operate. The relay armature 14 closes the circuit through the hell 4. The springs 45 and 46 draw the armature-s 43 and 44 into engagement with the contacts 47 and 48 of the ground coils 49 and 50, respectively, at

the outer terminus of the main circuit. The fact thatthe recorder does not print the code and the pointer 37 of the meter 6, swings to zero indicates to-the central station operator that a break exists in one of the main signal circuit lines 23, 25, which can be readily located by throwing the switch 22 into en gagement with the contact 22". This results in energizing the coil 42 which draws the armature 44'out of en agement with the contact 48. The ground circuit then enters at the rear of the break in the main signal circuit line 23 through the ground coil 49, contact 47, armature 43 and wire 51, the cur rent returning to central station A,through the main signal circuit wire 25 as before. This stops the recorder 3 from running out further tape after which the bell circuit 4 is cut out by manually restoring the armature 14 to normal position. As none of the house equipments were affected by the break in the main signal circuit line 23 the system is now ready for normal operation.

The same results occur when the main signal circuit wire 25 becomes broken, excepting that the ground circuit is completed by throwing the switch 22 to the contact 22", to which the current passes from the ground coil 50, which is automatically. placed in circuit with the main signal circuit line 25, through wire 52, armature 44 and the contact 48.

From the foregoing description it will be understood that I have provided a system whereby signals may be transmitted under, substantially, any condition which may arise due to accidents and fires, and while I have shown and described the preferred construction, combination and arrangement of parts, I reserve the right to make such changes properly fall within the spirit and scope of the claims.

Having thus described my invention, what I claim and desire to'secure by Letters Patent, is:

1. In a fire alarm system, a normally closed signal circuit, two normally closed house loops connected to said signal circuit,

a resistance in one house loop to normally reduce the flow of current therethrough below that in the other house loop, thermal means'for electrically connecting said house loops on an abnormal rise in temperature and thereby increasing the current in the highresistance loop, a transmitter for transmitting signals over said signal circuit, and means actuated by the increase in current for releasing the transmitter for signalling operation.

2. In a fire alarm system, a normally closed signal circuit, two normally closed house loopsconnected to said signal circuit, a shunt in series with said signal circuit and connected to one house loop, magnetic means energized by said shunt on breakage of the Luv connected house loop, a signaling device released by said energized magnetic means for transmitting a signal over said signal circuit, an element for checking said signaling device after transmission of a trouble si nal,

a resistance in one house loop to normally reduce the flow of current therethrough below that in the other house loop, thermal means for electrically connecting said house loops 011 an abnormal rise in temperature and thereby increasing the current in the high resistance loop, and means energized by said increase in current for disengaging said checking element from said signaling device so that the same may transmit an emergency fire alarm.

3. In a fire alarm system, a normally closed signal circuit, two normally closed house loops connected to said signal circuit, a shunt in series with said signal circuit and connected to one house loop, magnetic means energized by said shunt on breakage of the connected house loop, a signaling device released by said energized magnetic means for transmitting a signal over said signal circuit, an element for checking said signaling means after transmission of a trouble signal, a switch which shifts its position and opens said shunt when the signaling device is released, a second shunt bridged by the shifted switch and connected to the signal circuit to maintain the same in closed condition, a third shunt bridged by the shifted switch to close a path from the broken house loop to the signal circuit, a fourth shunt bridged by the shifted switch and leading from the unbroken house loop to the signal circuit, thermal means for electrically connecting the house loops on an abnormal rise in temperature, and magnetic means in said fourth shunt which is energized when said house loops are electrically connected and releases the signaling device for transmission of an emergency fire alarm signal.

4:. In a fire alarm system, the combination of a central station and its instruments. a signal circuit extending to a plurality of house equipments, each house equipment consisting of two house loops connected to said signal circuit, a shunt in series with said signal circuit and connected to one house loop, magnetic means energized by said shunt on breakage of the connected house loop, a signaling device released by said energized magnetic means for transmitting signal over said signal circuit, an element for checking said signaling device after transmission of a trouble signal, a switch which shifts its position and opens said shunt when the signaling device is released, a second shunt bridged by the shifted switch and connected to the signal circuit to maintain the same in closed condition, a third shunt bridged by the shifted switch to close a path from the broken house loop to the signal circuit, fourth shunt bridged by the shifted switch and leading from the unbroken house loop to the signal circuit, thermal means for electrically connecting the house loops on an abnormal rise in temperature, magnetic means in said fourth shunt which is energized when said house loops are electrically connected and releas s the signalin, means for transinfssion of an emergency iire alarm signal, and a switch which opens said fourth sl 1 t on comp etion of said emergency fire alarm signal.

5. In a fire alarm system, a normally closed signal circuit, two norn'ially closed house loops connected to said signal circuit, a circuit break-er in one house loop which is biased to open position, a magnetic coil in the other house loop to maintain the circuit breaker in closed position when said other house loop is intact and to permit said circuit breaker to open its associate; house loop when said other house loo breaks, a transmitter for transmitting signals over said signal circuit, and mean actuated by the opening of said one house loop for releasing the trans; itter for signaling oper ation.

6.111 a tire alarm system, a normally closed signal circuit, two normally closed house loops connected to said signal circuit, a resistance in one house loop to normally reduce the flow of current therethrough below that in the other house loop, thermal means for electrically connecting said house loops on an abnormal rise in temperature and thereby increasing the current in the high resistance loop, a transmitter for sending signals over the signal circuit, and magnetic means energized by the increase of current in the high resistance loop for releasing said transmitter.

7. In a tire alarm system, a normally closed signal circuit, a number of house equipments each of which consists of two normally closed house loops connected to said signal circuit, a resistance in one house loop to normally reduce the flow of current therethrough below that in the other house loop, thermal means for electrically connecting said house loops on an abnormal rise in temperature and thereby increasing the current in the high resistance loop, a transmitting device which is released by the increase of current for transmitting si nals over said signal circuit, magnetic means energized by said increase in current, a shiftable switch normally held in position to close the house loops and the signal circuit and which is released by said energized magnetic means to shift its position and cut out the house loops, and a shunt closed by the shifted switch and connected to the signal circuit to maintain the same in closed position.

8. In system of the character described, a normally closed signal circuit, a plurality of house equipments, each consisting of a house loop in series with said signal circuit, a second house loop connected across said signal circuit, a switch normally closing said house loops, a resistance in said second house loop to normally reduce the flow of cur rent therethrough below that in said first house loop, thermal means for electrically connecting both house loops on an abnormal rise in temperature so that the current from the first house loop may reinforce the cur-1 rent in the second house loop, a signaling device in circuit with said signal circuit, mechanism for actuating said signaling device and releasing said switch so that the latter may open both house loops, and magnetic means energized by said reinforced current for releasing said actuating mechanism so that the switch may open both house loops and restore the signal circuit to closed condition for maintaining the circuit connections with the other houseequipments.

9. In a system of the character described, a normally closed signal circuit, a plurality of house equipments, each consisting of a house loop in series with said signal circuit,

a second house loop connected across said signal circuit, a switch normally closing said house loops, a resistance in said second house loop to normally reduce the flow of current therethrough below that in said first house loop, thermal means for electrically connecting both house loops on an abnormal rise in temperature so that the current in the first house loop may reinforce the current in the second house loop, a signaling device in circuit with said signal circuit, mechanism for actuating said signaling device and releasing said switch, a normally open shunt connected to said signal circuit and closed by the switch in released position, and magnetic means energized by said reinforced Clll'l'QIlilfOl releasing said actuating mechanism so that the switch may open both house loops and close said shunt to restore the signal circuit to closed condition for maintaining the circuit connections with the other house equipments.

In testimony whereof I atlix my signature.

JOHN M.JOHNSON.. 

